Small Dispacement Nitro/methanol NA 2S engine questions
Small Dispacement Nitro/methanol NA 2S engine questions
(OP)
Greetings!
I build/race model airplanes. My latest project is to attempt to bump up the power delivery and RPM of an engine I'm using in a particular airframe.
It's called a Moki 210. 2.10cid (34.4cc) with a 36mmbx34mms.
These engines come from Europe where nitromethane is next to impossible to get. That being said they are designed/intended to run on a blend of methanol and bean/castor oil. Here in the states we can buy nitro but due to the compression ratio only about 10% will work with the stock CR.
I own a full service CNC machine shop. I am making a new crank (stock ones don't last much past 10K rpm) new rod, and a piston using no rings. I plan on running a tapered bore with a choke near TDC that'll open up once the engine warms up to operating temp.
I'd like help with configuring a good CR for a 50% nitro/50% methanol blend. I'm guessing around 8:1-9:1.
The end goal is to spin a 16" X 16" pitch prop at 15,000rpm. Right now the engine will run it at 7400. At 15K this gives me a round about speed potential of 225mph. That's ignoring things like drag. I'm guessing 170-180 is more likely. Plenty fast for this airframe. (terrifying fast for this plane actually)
Thoughts, comments, suggestions, and help is much appreciated!
C
I build/race model airplanes. My latest project is to attempt to bump up the power delivery and RPM of an engine I'm using in a particular airframe.
It's called a Moki 210. 2.10cid (34.4cc) with a 36mmbx34mms.
These engines come from Europe where nitromethane is next to impossible to get. That being said they are designed/intended to run on a blend of methanol and bean/castor oil. Here in the states we can buy nitro but due to the compression ratio only about 10% will work with the stock CR.
I own a full service CNC machine shop. I am making a new crank (stock ones don't last much past 10K rpm) new rod, and a piston using no rings. I plan on running a tapered bore with a choke near TDC that'll open up once the engine warms up to operating temp.
I'd like help with configuring a good CR for a 50% nitro/50% methanol blend. I'm guessing around 8:1-9:1.
The end goal is to spin a 16" X 16" pitch prop at 15,000rpm. Right now the engine will run it at 7400. At 15K this gives me a round about speed potential of 225mph. That's ignoring things like drag. I'm guessing 170-180 is more likely. Plenty fast for this airframe. (terrifying fast for this plane actually)
Thoughts, comments, suggestions, and help is much appreciated!
C





RE: Small Dispacement Nitro/methanol NA 2S engine questions
RE: Small Dispacement Nitro/methanol NA 2S engine questions
Mike Halloran
Pembroke Pines, FL, USA
RE: Small Dispacement Nitro/methanol NA 2S engine questions
Good luck, you're going to need it. BTW, nitro is widely available in Europe, it just costs a lot. 50% pop is what Fox Blast was, and a lot of guys ruined a lot of engines with it.
A 50/50 blend doesn't have any lube. Castor doesn't mix well with NM, and with 50%NM, 35% meth and 15% castor you can expect mixing problems, especially in cool weather.
You can blend in ~10% nitrobenzene which will dissolve the castor and/or use some synthetic oil in place of some of the castor, but 50% with a big model engine is asking for problems. NB is also quite poisonous, unlike NM.
What material did you make the crank and rod from?
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein